Mine

// on the html form:

<td width="<?php echo $rightCell?>%" > 
			<input width="200" name="BannerFile" id="BannerFile" type="file" class="registerForm" value=
'
<?php if (isset($_SESSION["banner_state_filename"])) 
{
echo $_SESSION["banner_state_filename"]; 
unset($_SESSION["banner_state_filename"] );} 
?>
'/>
</td>


// on the php script:
$banner = $_FILES["BannerFile"]["name"];
print_r($_FILES);
print_r($_FILES["BannerFile"]);

if (isset($_FILES["BannerFile"]))
{
        echo "OK"; 
        exit();
}
if ($banner == "") 
{
	//echo 'banner is '. $banner;
	// $_SESSION["newbanner_error"] = "filename";
	//header ("Location: bannernou.php");	
	exit();
}